Moses thompson



UNITED STATES PATENT OFFICE.

MOSES THOMPSON, OF NEW YORK, N. Y.

BAGASSE-FURNACE Specification of Letters Patent No. 18,874, dated December 15, 1857.

T 0 all 'whom t may concern:

Be it known that I, Moses THOMPSON, late of New Orleans, Louisiana, but now of the city, county, and State of New York, have invented new and useful improvements in furnaces for using as fuel bagasse, wet tan, and other carbonaceous substances too wet to be conveniently burned in the usual way, of which the following is a full and exact description, reference being had to the accompanying drawings, making a part thereof, in which- Figure l, is a front view of my furnace. Fig. 2, is a sectional side view showing the interior thereof, and the charge of wet fuel, &c. Fig. 3, is a front sectional view. Fig. et, is a horizontal view of the grate. Fig. 5, is a sectional perspective view of the interior showing the corrugations, &c., in the wet fuel chamber.

The same parts are designated by the same letters on all the figures.

The leading object of my invention is to use, as far as possible the hot vapors driven out of the wet mass while drying instead of cold common air to support and complete the combustion of the carbonaceous portions of the wet fuel.

Bagasse and other wet fuel might be advantageously burned in one furnace, but re sults are much more uniform and reliable when two are used discharging their gases into a common mixing chamber and I therefore prefer to use two or more.

The grate surface, and the height of the furnace should be regulated according to the kind and wetness of the fuel, the wetter the fuel the larger the furnace and the smaller the .mixing chamber should be. To burn hagasse for making ten or twelve hogsheads of sugar per day I make my furnaces each about ten feet square and twenty-two feet high. For making greater or smaller quantities of sugar I increase or diminish the size of the furnace; but for making smaller quantities the size of the furnace should diminish in a less proportion than the quant-ity o-f sugar, and for larger quantities the size should increase in a less proportion than the quantity of sugar. For burning refuse tan and saw-dust I think it better to make the furnace longer and narrower with two fuel openings on the top, and for a furnace five feet wide and ten feet long I would make the height from the bottom of the fire chamber to the top of the wet fuel chamber about five feet. The bott-om of the grate I would place about two feet above the hearth. But wet fuels differ so much in character and wetness that it is impossible to give precise dimensions.

The furnace I propose to describe is particularly calculated to consume bagasse.

I build two furnaces side by side each nearly square in its horizontal section. Toward the top I draw in the wall in such manner as to form a kind of dome with a. sufficient opening at top to feed the bagasse. 'Ihe outer walls of these furnaces should be from 24 to 30 inches thick and built with a special View to rendering them nonconducting, the wall near the top, and the partition between the two furnaces may be thinner. In each furnace chamber there should be a partition of fire brick extending across it from front to back and rising nearly to the top dividing it into two nearly equal parts. The whole interior of the furnace should be of fire brick. The main chamber of each furnace should be divided into two parts--upper and lower-by a fire brick grate about one-fifth the height of the furnace above the hearth, the back end of the grate being a little lower than the front. The bottom of the lower chamber may be a grate with an ash pit, but a hearth is much better.

In each furnace at the front, on each side of the central partition and immediately under the front end 0f the grate should be doors for feeding wood or other dry fuel, and directly under these doors at the hearth of the lower chamber should be draft openings capable of adjustment to supportcombustion in the lower chamber.

Extending across the back of both furnaces, and opening into both by flues is a mixing chamber into which all the gases from both furnaces enter in a highly heated state and mix and consume each other on their way to the boiler and stack. This chamber should be about one half the capacity of all the fire chambers and it should extend down about as low as the back end of the grate. The flue through which the products of combustion pass out of this chamber and under the boiler should be in section about one square foot to forty cubic feet of mixing chamber.

The feed openings at the top of the furnaces should be closed by doors which open inward by the weight of the feed, but are self closing, and do not yield to pressure from within. i

The sides of the interior of the upper or wet fuel chamber or drying chamber of the furnace, except the front and back, are corrugated up and down, as also the sides of the central walls or partitions as shown in Fig. 5, the corrugations extending down to the grate; These corrugations are for the purpose of allowing the heat to radiate upward from the fire chamber for heating the masonry and the wet charge, while the gases or vapors driven out of the wet charge by the heat are allowed to descend. to the fire chamber or the mixing chamber. If the surfaces of this masonry were smooth the bagasse would lie against them in such a manner as to obstruct the upward radiation of the heat and the downward passage of the vapors. These corrugations are unneces sary in burning tan and saw-dust.

The spaces between the grate bars for` burning'bagasse should be about 6 ins. wide for the finest grinding and twenty inches for the coarsest and should vary between these widths according to the ineness of grinding, but for saw-dust and tan much less, say from one inch to of an inch. The grade should be made of fire brick.

The operation of my furnace is as follows: A hot lire of dry fuel is kindled in the lower or fire chamber of the the furnaces and after it has been continued until the masonry is well heated, the chamber above the grate is fed with the bagasse or other wet fuel. This hot lire in the fire chamber especially towar'd the front of it under the principal mass of the wet fuel must be preserved throughout the operation. The heat from the masonry and the fire chamber will be communicated to the wet fuel, which will cause steamvand other gases to issue from it and mix with the intensely hot gases of com* bustion from the fire chambers, and in a short time the mixing chamber will present intense conbustion and heat, the dampers of the fire chambers being partially closed. The lower part of the wet charge'will by degrees become dry and charred and will fall through the grate prepared as above into the fire chamber and supply or nearly supply the place of other dry fuel in preserving the fire in this chamber, and the wet fuel being from time to time suppliedwill furnish in a highly heated state, aqueous vapors which descending through the corrugations and otherwise into the fire chamber and mixing chamber, will be decomposed, furnishing much oxygen to the fire, and supply the oxygen necessary to complete in the mixing chamber the combustion of all the combustible gases issuing from the lire chamber. If by accident the fire in the lower part of the furnace should predominate the draft should be diminished and more wet fuel added, and, if by accident, the fire in the fire chamber should become too much cooled down the draft should 'be left on, and any deficiency of dry fuel should be supplied to the lire chamber. Under proper management little or no dry fuel need be fed to the fire chamber after the operation is fairly commenced. The charred matter falling through the open grate will supply its place, and the caloric thus produced by the combustion of wet fuel will be vastly greater than from the same quantity by measure of the same fuel when dry. yIn the fire chamber and in the mixing chamber under intense heat the carbonaceous gases will decompose the steam from the wet fuel and effect com plete combustion. When the operation is fairly commenced, if the water in the wet' charge amounts to, say fifty per cent. by weight of the fuel, the dampers of the fire chambers should be nearly or quite closed to exclude the air. Vapor from the wet charge will then descend through the corrugations and otherwise into the fire chambers and support the combustion therein, while other portions of the vapor will enter the mixing chamber and complete the combustion there. 1f the fuel however contains much smaller quantities of water, more air in proportion should be admitted at the damper, the object being to admit no more air than will supply the deficiency of the vapor.

In the drawings D represent the chambers for the dry fuel, W those for the wet, M the mixing chamber, the dotted line m limits it for the wettest bagasse, P the partition, F the feed opening for the wet fuel with their doors, G the corrugations, a the openings for draft, f doors for feeding dry wood. B the boiler, b, the bridge, and A the ash pit beyond the bridge. Little if any of the boiler should extend over the mixing chamber. If any considerable portion of the mixing chamber is covered by the boiler its cooling iniiuence ,will prevent the 'decomposition of the vapor and defeat the object of my invention.

Great care should be observed in giving proper dimensions to the mixing chamber, for the perfection of the combustion and the efliciency of the furnace depend greatly upon it. The principal object of this chamber is to give the combustible carbonaceous gases from the re, and the aqueous gases from the mass of wet fuel an opportunity of mingling together in such a manner and under such circumstances that the aqueous vapor will be decomposed by the carbonaceous gases, and its oxygen given out to complete the combustion of the carbon without the introduction of air into the mixing chamber, thus saving the caloric previously communicated to the wet charge, while drying it and charring its lower portions, and avoiding the cooling influences of cold air.

This can take place eifectually only in the presence of a high degree of heat and in the absence of a supply of free oxygen. If this chamber be too small to receive these gases as fast as the furnace is able to produce them, the operation will of course be choked and impeded. If the chamber is larger than can be kept densely filled with these gases, of course atmospheric air will be found there at the commencement, and will continue to find its way into the chamber, and while atmospheric air is present, the carbonaceous gases will take its oxygen from that principally, instead of decomposing the steam, and the heat in the chamber will be much diminished and the large quantity of nitrogen -4/5- contained in the air, which is neither a combustible nor a supporter of combustion, will at once greatly increase the volume of gases to be sent forward to the stack and proportionably decrease its temperature, and when the chamber becomes very large the cooling influences become so great that combustion will immediately cease, and smoke mingled with steam, oxygen and nitrogen will go forward, thus wasting the fuel and imparting a faint degree of heat to the boiler. I have therefore xed the size of the mixing chamber by many careful experiments-and that given above will produce the desired effect with wet bagasse. For drier fuel furnishing less vapor, the mixing chamber should be proportionably increased in size to supply t-he deiiciency with air and to eect completecombustion. Rules more precise would be in consistent with the nature of the subject. A large and hot re should always be preserved in the fire chamber below the grate, and directly under the charge of wet fuel, for the purpose of driving the vapor out of it and charring its lower portion-and the grate is left much more open than in furnaces for burning dry fuel of the same size, for the purpose of allowing the charred portions of the wet charge to fall through to supply fuel for this re, as fast as it becomes fit for that purpose, thus consuming the nas with little or no expenditure of other vue What I claim as my improvement in fur naces for burning bagasse and other fuels too wet to be conveniently burned in the usual and well known ways is:

l. The combination of two chambers the one above the other, and separated by a grate, the lower one for the combustion of any known dry carbonaceous fuel, and the upper one in immediate proximity therewith to receive heat therefrom for heating and drying the charge of wet fuel, with a mixing chamber, into which both continuously and simultaneously discharge their gases before reaching the thing to be heated, for mingling and mutual combustion.

2. I also claim in combination with said fire chamber and wet fuel chamber or drying chamber, making the grate upon which the wet charge rests suiiiciently open to allow the lower portion of the wet charge as it becomes dried and charred to fall through into the fire chamber and keep a hot fire therein, supplying the place of other dry fuel, while the uncharred portion of the wet fuel is properly supported by the grate t'ill dried, as described.

3. I also claim placing the mixing chamber of combustion in substantially the same position described relatively to the lire, and the wet charge, so that the products of combustion from the dry fuel may pass along the lower part of the wet charge drying and charring it on their way to the mixing chamber and reach it without being in any considerable degree obstructed or cooled by the wet charge substantially as shown.

I wish it distinctly understoood that I make no claim to any of the parts or combinations above specified except in their application to the preparation and combust-ion of wet fuels.

MOSES THOMPSON.

In presence of WM. H. WrLLcox, JOHN J. MURRAY. 

